Ground detection for touch sensitive device

ABSTRACT

Ground detection of a touch sensitive device is disclosed. The device can detect its grounded state so that poor grounding can be selectively compensated for in touch signals outputted by the device. The device can include one or more components to monitor certain conditions of the device. The device can analyze the monitored conditions to determine the grounding condition of the device. The device can apply a function to compensate its touch signal outputs if the device determines that it is poorly grounded. Conversely, the device can omit the function if the device determines that it is well grounded.

FIELD

This relates generally to touch sensitive devices and, moreparticularly, to detecting a grounded state of a touch sensitive device.

BACKGROUND

Many types of input devices are presently available for performingoperations in a computing system, such as buttons or keys, mice,trackballs, joysticks, touch sensor panels, touch screens and the like.Touch sensitive devices, such as touch screens, in particular, arebecoming increasingly popular because of their ease and versatility ofoperation as well as their declining price. A touch sensitive device caninclude a touch sensor panel, which can be a clear panel with atouch-sensitive surface, and a display device such as a liquid crystaldisplay (LCD) that can be positioned partially or fully behind the panelso that the touch-sensitive surface can cover at least a portion of theviewable area of the display device. The touch sensitive device canallow a user to perform various functions by touching the touch sensorpanel using a finger, stylus or other object at a location oftendictated by a user interface (UI) being displayed by the display device.In general, the touch sensitive device can recognize a touch event andthe position of the touch event on the touch sensor panel, and thecomputing system can then interpret the touch event in accordance withthe display appearing at the time of the touch event, and thereafter canperform one or more actions based on the touch event.

When the touch sensitive device is poorly grounded, recognizing a touchevent can become difficult. The poor grounding can cause touch valuesrepresenting the touch event to be erroneous or otherwise distorted byundesirable capacitive coupling introduced into the device.Consequently, actions to be performed based on the touch event canlikewise be erroneous or otherwise distorted.

SUMMARY

This relates to ground detection for a touch sensitive device. Thedevice can detect its grounded state so that poor grounding can becompensated for in touch signals outputted by the device. The device caninclude one or more components that monitor certain conditions of thedevice. The device can analyze the monitored conditions to determinewhether the device is grounded. The device can selectively apply afunction to compensate its touch signal outputs if the device determinesthat it is poorly grounded. Conversely, the device can selectivelyignore the function if the device determines that it is well grounded.Ground detection can advantageously provide improved touch sensing andpower savings by not having to repeat measurements subject to poordevice grounding. Additionally, the device can more robustly adapt tovarious grounding conditions.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an exemplary touch sensitive device having aconnector sensor that can be used for detecting a grounded state of thedevice according to various embodiments.

FIG. 2 illustrates an exemplary touch sensitive device having a motionsensor that can be used for detecting a grounded state of the deviceaccording to various embodiments.

FIG. 3 illustrates an exemplary touch sensitive device having aproximity sensor that can be used for detecting a grounded state of thedevice according to various embodiments.

FIG. 4 illustrates an exemplary touch sensitive device having aperimeter sensor that can be used for detecting a grounded state of thedevice according to various embodiments.

FIG. 5 illustrates an exemplary touch sensitive device having anotification algorithm that can be used for detecting a grounded stateof the device according to various embodiments.

FIG. 6 illustrates an exemplary touch sensitive device having a touchsensor panel that can be used for detecting a grounded state of thedevice according to various embodiments.

FIG. 7 illustrates an exemplary method for detecting a grounded state ofa touch sensitive device according to various embodiments.

FIG. 8 illustrates an exemplary computing system of a touch sensitivedevice that can detect a grounded state of the device according tovarious embodiments.

FIG. 9 illustrates an exemplary mobile telephone that can detect itsgrounded state according to various embodiments.

FIG. 10 illustrates an exemplary digital media player that can detectits grounded state according to various embodiments.

FIG. 11 illustrates an exemplary personal computer that can detect itsgrounded state according to various embodiments.

FIG. 12 illustrates an exemplary method for detecting a state of a touchsensitive device according to various embodiments.

DETAILED DESCRIPTION

In the following description of various embodiments, reference is madeto the accompanying drawings which form a part hereof, and in which itis shown by way of illustration specific embodiments which can bepracticed. It is to be understood that other embodiments can be used andstructural changes can be made without departing from the scope of thevarious embodiments.

This relates to detecting a grounded state of a touch sensitive device.The device can selectively compensate touch signal outputs for errorintroduced into the outputs as a result of the device's grounded state.When the device is poorly grounded, the device can apply thecompensation. When the device is well grounded, the device can omit thecompensation. In some embodiments, to detect the grounded state, thedevice can check one or more parameters which can be indicative of thedevice's grounding. The device can analyze the parameters' values todetermine whether the device is grounded. The device can selectivelyapply the compensation in accordance with the grounded determination.

The ability to detect how well grounded a touch sensitive device is canadvantageously provide more accurate and faster touch sensing by nothaving to repeat measurements subject to poor device grounding. Powersavings can also be realized by not having to repeat measurements.Additionally, the device can more robustly adapt to various groundingconditions.

The terms “poorly grounded,” “ungrounded,” “not grounded,” “not wellgrounded,” “improperly grounded,” “isolated,” and “floating” can be usedinterchangeably to refer to poor grounding conditions that can existwhen the touch sensitive device is not making a low resistanceelectrical connection to ground.

The terms “grounded,” “properly grounded,” and “well grounded” can beused interchangeably to refer to good grounding conditions that canexist when the touch sensitive device is making a low resistanceelectrical connection to ground.

Although various embodiments can be described and illustrated herein interms of touch sensitive devices, it should be understood that thevarious embodiments are not so limited, but can be additionallyapplicable to any device for which the device's grounded state can bedetermined and the device can be selectively adjusted to correct,improve, or otherwise change the device's state, operation, output, andthe like.

When a well grounded touch sensitive device receives a touch by anobject, such as a user's fingers, the device's mutual signal capacitanceCsig at the touch location can be properly changed to produce a pixeltouch output value indicative of a true touch event. However, when apoorly grounded touch sensitive device receives a touch by an object,such as a user's fingers, undesirable charge coupling called negativecapacitance Cneg can be introduced into the device to cause the pixeltouch output value to be in the opposite direction of the intendedmutual capacitance change. As such, a pixel experiencing touch underpoor grounding conditions can appear to detect less of a touch than isactually present, known as a “negative pixel.” Negative pixelcompensation can be selectively applied to the negative pixel touchoutput value to reduce or eliminate the negative pixel effect. However,to be effective, the negative pixel compensation should be applied underappropriate conditions and in appropriate amounts. Since negativecapacitance Cneg can be a function of how well the touch sensitivedevice is grounded, the device's grounded state can be detected so thatnegative pixel compensation can be applied as needed. The detection canbe done by monitoring various touch sensitive device parametersindicative of the device's grounding and determining the grounding basedon the monitored parameters' values. FIGS. 1 through 6 illustrateexemplary device parameters and corresponding device components thatdetermine the parameters' values which can be used for detecting agrounded state of a touch sensitive device according to variousembodiments.

FIG. 1 illustrates an exemplary touch sensitive device having connectorsensors and detectors that can be used for detecting the device'sgrounded state according to various embodiments. In the example of FIG.1, touch sensitive device 10 can include touch panel 11, which canreceive a touch by an object and produce touch signals (or touch outputvalues) indicative of that touch. The touch sensitive device 10 can alsoinclude one or more connector ports 10 a, 10 b, and 10 c for connectingto various components. Connector port 10 a can connect the touchsensitive device 10 to power cable 12 (the connection symbolicallyillustrated by the circle “1”). The power cable 12 can connect to a walloutlet or some other AC power supply to power the device 10. Connectorsensor 13 a can sense power from the power cable 12 via the connectorport 10 a. The sensed power can indicate that the device 10 is pluggedinto a wall outlet, for example, thereby grounding the device throughthe wall ground. Therefore, sensing power via the connector port 10 acan indicate that the touch sensitive device 10 is grounded such thatnegative pixel compensation can be either deactivated or reduced, ifcurrently active, or can remain inactive otherwise, when the touch panel11 produces touch signals.

Connector port 10 b can connect the touch sensitive device 10 to USBcable 16 (the connection symbolically illustrated by the circle “2”).The USB cable 16 can connect to a USB port of another device, e.g., acomputer, to power the touch sensitive device 10 and/or transmit databetween the touch sensitive device and the connecting device. Connectorsensor 13 a can sense the USB connection via the connection port 10 b.The sensed connection can indicate that the device 10 is coupled to acomputer, for example, thereby grounding the device through the computerground. Therefore, sensing the connection via the connector port 10 bcan indicate that the touch sensitive device 10 is grounded such thatnegative pixel compensation can be either deactivated or reduced, ifcurrently active, or can otherwise remain inactive, when the touch panel11 produces touch signals.

Connector port 10 c can connect the touch sensitive device 10 toconnector port 18 c of dock 18 (the connection symbolically illustratedby the circle “3”). The dock 18 can in turn connect to either the powercable 12 via dock connector port 18 a (the connection symbolicallyillustrated by the circle “1”) or the USB cable 16 via dock connectorport 18 b (the connection symbolically illustrated by the circle “2”).The touch sensitive device 10 can receive power from the power cable 12through the dock connections. The touch sensitive device 10 can alsoreceive power and/or data from the USB cable 16 through the dockconnections. Resistor pin 13 b in the connector port 10 c can connect toa resistor of the connecting component, e.g., a resistor of either thepower cable 12 or the USB cable 16. When the resistor pin 13 b sees aresistance characteristic of the connecting component, the device 10 canidentify from that resistance the component, e.g., the cable, to whichthe device is connected. For example, if the dock 18 is connected to thepower cable 12, the resistor pin 13 b can identify the characteristicresistance of the power cable and the device 10 can determine that it isconnected to the power cable. The device 10 can use the identification(and other information, if needed) to determine its grounded state. Forexample, the device 10 can identify its connection to the power cable 12via the resistor pin 13 b. Therefore, sensing the resistance via theresistor pin 13 b can indicate that the touch sensitive device 10 isgrounded via the power cable's connection to a wall outlet or other ACpower supply such that negative pixel compensation can be eitherdeactivated or reduced, if currently active, or can otherwise remaininactive when the touch panel 11 produces touch signals. Similardeterminations can be made regarding the USB cable's connection betweenthe dock 18 and a computer, for example.

In some embodiments, the dock 18 can include a resistor 18 d, such thatthe resistor pin 13 b can sense the dock's characteristic resistance andthe device 10 can determine that it is connected to the dock. The device10 can sense the dock's resistor in cases where neither the power cable12 nor the USB cable 16 are connected to the dock 18 and therefore tothe device. This can be an indication that the device 10 is notconnected to a grounded device and therefore is not grounded. As such,negative pixel compensation can be adjusted, if currently active, oractivated, if currently inactive, for applying to touch signals.

In some embodiments, the connector port 10 c of the touch sensitivedevice 10 can have additional pins, including a USB pin (not shown) toindicate a connection to the USB cable 16 through the dock 18 and apower pin (not shown) to indicate a connection to the power cable 12through the dock. When these device pins sense a USB signal or power,the device 10 can determine whether it is sufficiently grounded suchthat negative pixel compensation can be either deactivated or reduced,if currently active, or can otherwise remain inactive, when the touchpanel 11 produces touch signals.

The connector port 10 c can also connect the touch sensitive device 10to adapter cable 14 (the connection symbolically indicated by the circle“3”). The adapter cable 14 can connect to a wall outlet or some other ACpower supply to power the device 10. The resistor pin 13 b in theconnector port 10 c can sense the characteristic resistance of theadapter cable 14 and the device 10 can identify that it is connected tothe adapter cable. The device 10 can use the identification (and otherinformation, if needed) to determine its grounded state. Sensing theresistance via the resistor pin 13 b can indicate that the touchsensitive device 10 is grounded such that negative pixel compensationcan be either deactivated or reduced, if currently active, or canotherwise remain inactive, when the touch panel 11 produces touchsignals.

In some embodiments, different power cables can result in differentgrounding conditions for the touch sensitive device. For example, onetype of power cable connectable to the device can have three prongs suchthat the device ground can directly connect to the wall ground,resulting in a well grounded device. As such, negative pixelcompensation can be deactivated or reduced, if currently active, or canotherwise remain inactive, when the touch panel produces touch signals.Another type of power cable connectable to the device can have twoprongs and a relatively high net capacitance, resulting in a poorlygrounded device. As such, negative pixel compensation can be adjusted,if currently active, or activated, if currently inactive, for applyingto touch signals. Another type of power cable connectable to the devicecan have two prongs and a relatively low net capacitance, resulting in abetter grounded device. As such, negative pixel compensation can beeither deactivated or adjusted as needed, if currently active, or eitheractivated or adjusted as needed, if currently inactive, for applying totouch signals.

Additional and/or other connecting components and combinations can beused to determine a grounded state of the touch sensitive deviceaccording to various embodiments.

FIG. 2 illustrates an exemplary touch sensitive device having motionsensors that can be used for detecting the device's grounded stateaccording to various embodiments. In the example of FIG. 2, touchsensitive device 20 can include touch panel 21, which can receive atouch and produce touch signals indicative of the touch. The touchsensitive device 20 can also include motion sensor 22 to sense thedevice's orientation and motion. Example motion sensors can includeaccelerometers, gyroscopes, and the like. Sensing the orientation andmotion of the device 20 can give an indication of the device's currentstatus, which can be indicative of the device's grounded state. Forexample, if the motion sensor 22 of the device 20 senses a particularpattern, frequency, and/or magnitude of vibrations unique to humans, thedevice can determine that it is in contact with a user, e.g., beingheld, and therefore grounded. These patterns, frequencies, and/ormagnitudes can be predetermined or can be “learned” if the user placesthe device into a learning state while holding, moving, or walking withthe device, for example. As such, negative pixel compensation can bedeactivated or reduced, if currently active, or can otherwise remaininactive, when the touch panel 21 produces touch signals. If the motionsensor 22 senses motion that is determined not to be human vibrations,the device 20 can use additional information about the object moving thedevice to determine whether the device is grounded. Conversely, if themotion sensor 22 senses that the device 20 is substantially stationaryand/or oriented in a particular manner, the device can determine that itis in a dock or on a surface. If in a dock, the device 20 can useadditional information, e.g., the dock connections, to determine whetherthe device is grounded. If on a surface, the device 20 can useadditional information, e.g., the device connections or the surface, todetermine whether the device is grounded. The device 20 can selectivelyapply negative pixel compensation to the touch signals based on thedetermination.

FIG. 3 illustrates an exemplary touch sensitive device having proximitysensors that can be used for detecting the device's grounded stateaccording to various embodiments. In the example of FIG. 3, touchsensitive device 30 can include proximity sensors 34 for sensingsurfaces proximate to the device. The touch sensitive device 30 can alsoinclude a touch panel (not shown) for receiving a touch and producingtouch signals indicative of the touch. In some embodiments, theproximity sensors 34 can be disposed at a back surface of the touchsensitive device 30 (as shown in FIG. 3) to sense the surface proximateto the back of the device or that the device rests against. In someembodiments, the proximity sensors 34 can be disposed at a side surfaceof the touch sensitive device 30 to sense the surface proximate to thesides of the device or that the device rests against. In someembodiments, the proximity sensors 34 can be disposed at a front surfaceof the touch sensitive device 30 to sense the surface proximate to thefront of the device or that the device rests against. In someembodiments, the proximity sensors 34 can be disposed at multiplelocations of the device, including the back, the sides, the front, andso on. Example proximity sensors can include capacitive, infrared,optical, ultrasound, etc., sensors.

Sensing a surface proximate to the touch sensitive device 30 canidentify the type of surface, e.g., wood, metal, plastic, organic,inorganic, human, and so on. For example, sensing a proximate humansurface can be an indication that the device 30 is being held by a useror resting in the user's lap and therefore grounded. As such, negativepixel compensation can be deactivated or reduced, if currently active,or can otherwise remain inactive. Sensing a proximate wood surface canbe an indication that the device 30 is resting on a table top andtherefore likely poorly grounded. As such, negative pixel compensationcan be adjusted, if currently active, or activated, if currentlyinactive, to apply to touch signals from the touch panel. Sensing arubber surface can be an indication that the device 30 is in aprotective case and therefore likely poorly grounded, even if held bythe user since the rubber can act as an insulator. As such, negativepixel compensation can be adjusted, if currently active, or activated,if currently inactive, to apply to touch signals. In some embodiments,when a surface is proximate to the device 30, the proximity sensor 34can sense a capacitance of the object having the proximate surface.Based on the sensed capacitance, the device 30 can identify theproximate surface.

In some embodiments, other property sensors can be used to sense one ormore identifying physical properties of the surface. Example propertiescan include temperature, texture, refractivity, conductivity,permeability (ability of material to respond to a magnetic field),density, and the like. For example, a density sensor can sense a densityof an object in the volume of space near the device 30, a temperaturesensor can sense a temperature of an object proximate to the device, andso on. Values of properties for various surfaces can be stored in memoryand compared to the sensed properties to identify the proximate surface,for example. Based on the identified proximate surface, the device candetermine its grounded state and whether negative pixel compensationshould be applied.

In some embodiments, other sensors can be used in conjunction with theproximity sensors 34 to detect the grounded state of the touch sensitivedevice 30. For example, the proximity sensors 34 can be used inconjunction with the motion sensors of FIG. 2 to determine whether thetouch sensitive device 30 is laying flat on a surface and what type ofsurface and, from at least this information, determine the device'sgrounded state. Based on this determination, the device 30 canselectively apply negative pixel compensation to the touch signals.

FIG. 4 illustrates an exemplary touch sensitive device having perimetersensors that can be used for detecting the device's grounded stateaccording to various embodiments. In the example of FIG. 4, touchsensitive device 40 can include touch panel 41 to receive a touch andproduce touch signals indicative of the touch. The touch sensitivedevice 40 can also include sensor 42 around the perimeter of the devicefor sensing a user's hand 45 or other object touching or holding thedevice. The sensor 42 can be around the perimeter because a user islikely to touch the perimeter of the touch sensitive device 40 as theuser holds the device. However, it is to be understood that the locationof the sensor is not limited to the perimeter, but can be disposedanywhere on the device that a user is likely to touch or hold.

In some embodiments, the sensor 42 can be a capacitive sensor to sense atouch at the device 40. The capacitive sensor can be a self capacitancesensor, in which a conductive electrode disposed around a perimeter ofthe touch sensitive device 40 can be charged to generate fringingelectric fields around the perimeter edges and form a self capacitancewith respect to ground. A grounded object, e.g., a user's hand, cancapacitively couple with the electrode as the object touches the device,thereby adding to the self capacitance. The increase in the selfcapacitance of the electrode can be measured by the device 40 todetermine whether the object is touching the device. In addition oralternative to a signal charging the perimeter electrode, a signal canbe applied to all or portions of the touch sensitive device 40 andassociated electronics to generate electric fields between the deviceand a ground electrode, thereby forming a self capacitance with respectto ground.

In some embodiments, the capacitive sensor can be a mutual capacitancesensor, in which a pair of conductive electrodes can be disposed inclose proximity to each other around a perimeter of the touch sensitivedevice 40 and in which one of the electrodes can be charged (e.g.,stimulated with an AC voltage) to form fringing electric fields and amutual capacitance therebetween. A grounded object, e.g., a user's hand,can capacitively couple with the charged electrode as the object touchesthe device, thereby stealing charge away from the charged electrode andreducing the mutual capacitance. The reduction in the mutual capacitancecan be measured by the device 40 to determine whether the object istouching the device. The sensor 42 can sense a touch or hold on thefront, the back, and/or the sides of the device 40.

Sensing a touch on the device 40 can be an indication that the device isbeing held and therefore grounded. As such, negative pixel compensationcan be deactivated or reduced, if currently active, or can otherwiseremain inactive, when the touch panel 41 produces touch signals.

In some embodiments, multiple electrodes (in self capacitanceembodiments) or multiple pairs of electrodes (in mutual capacitanceembodiments) can be used rather than a single continuous electrode or asingle pair of continuous electrodes. The multiple electrodes can bedisposed single file around a perimeter of the touch sensitive devicewith small spaces between consecutive electrodes. In addition to thedevice determining that a user has touched the device based on sensedsignals from the electrodes, the device can determine the location ofthe touch based on which electrodes transmitted the sensed signals.Similarly, in some embodiments, a segmented electrode or a segmentedpair of electrodes can be used rather than the single continuouselectrode or the single pair of continuous electrodes.

In some embodiments, the touch sensitive device can include a pair ofshielding electrodes disposed along both sides of the perimeter sensor(electrode or electrode pair) around the perimeter of the device. Theshielding electrodes can be used to isolate the capacitive coupling atthe sensor location of the device and minimize parasitic cross coupling,thereby improving the sensing of a touch at the other locations of thedevice. For example, the perimeter sensor can be located on the frontsurface of the device with the shielding electrodes around the sensor sothat capacitive coupling and touch sensing at the back surface of thedevice can be improved. Improved touch sensing at the back surface canbe useful for instances when a user is more likely to contact the backof the device than the front, e.g., when the user cradles or cups thedevice in the user's hands.

As shown in FIG. 4, the perimeter sensor can be on the front of thedevice. In some embodiments, the perimeter sensor can be on the sides ofthe device. In some embodiments, the perimeter sensor can be on the backof the device. In some embodiments, the perimeter sensor can be oncombinations of the front, the sides, and the back depending on theneeds of the device.

FIG. 5 illustrates an exemplary touch sensitive device having anotification algorithm that can be used for detecting a grounded stateof the device according to various embodiments. In the example of FIG.5, touch sensitive device 50 can include touch panel 51, which canreceive a touch and produce touch signals indicative of the touch. Thetouch sensitive device 50 can also include processor 52 and memory 54.The memory 54 can store various applications 56 that can be executed bythe processor 52 to operate on the device 50. The memory 54 can alsostore notification algorithms 58 that can also be executed by theprocessor 52 to issue a notice when an application 56 is executed thatcould be affected by the device 50 being poorly grounded. For example,an application 56 that requires a user to touch the device 50 withmultiple fingers 55 at the same time can cause the negative pixeleffect, as described previously. As such, negative pixel compensationcan be applied to the multiple-finger touch signals produced by thetouch panel 51 when that application executes. Conversely, negativepixel compensation can be omitted when an application 56 that requiresthe user to touch the device 50 with only one finger executes.

In some embodiments, a notification algorithm can monitor theapplication log or other processing data and issue a notice when amultiple finger application executes. The notice can trigger thenegative pixel compensation to be applied. In some embodiments, amultiple finger application can send a message to the notificationalgorithm that it is running, causing the notification algorithm toissue a notice and trigger the application of negative pixelcompensation. In some embodiments, the notification algorithm can beincorporated into the application. In some embodiments, the notificationalgorithm can be separate and in communication with the application.

Example applications that can require multiple finger touches on thetouch sensitive device can include a virtual keyboard display, amultiple finger gesture input, and the like.

It is to be understood however that not only multiple fingerapplications, but other applications and/or operating conditions of thedevice can be affected by a poorly grounded device, causing thenotification algorithm to issue a notice upon execution of thoseapplications and/or detection of those conditions.

FIG. 6 illustrates an exemplary touch sensitive device having a touchsensor panel that can be used for detecting a grounded state of thedevice according to various embodiments. In the example of FIG. 6, touchsensitive device 60 can include touch sensor panel 61 for sensing atouch at the device. The touch sensor panel 61 can include multiple rowsof drive lines 62 and multiple columns of sense lines 63 with theintersections of the drive and sense lines forming touch pixels 64. Whenthe drive lines are charged, they can capacitively couple with the senselines to provide mutual capacitance (similar to that describedpreviously) and the sense lines can transmit a touch signal indicativeof a touch at the panel 61 to sensing circuitry (not shown). The touchsignals can be analyzed to determine the characteristics of the touch,including the location, orientation, shape, movement, and so on, of thetouch image generated by the touch. For example, a user's finger tiptouching the panel can produce a circular touch image. Multiple fingertips can produce multiple circular touch images adjacent to each other.A thumb can produce an oval touch image, which can be vertical,horizontal, or angular, depending on the orientation of the thumb whentouching the panel.

A user's grip of an item can typically pose the thumb at an angle on afront surface of the item with the fingers either on or encircling theback surface of the item. In the case of the touch sensitive device 60,a user's grip 65 can pose the thumb at an angle on the front of thedevice at a lower corner. Consistently, the touch image of the thumbproduced by the touch panel 61 can have an oval shape at a lower cornerof the image with an angular orientation.

Accordingly, sensing a touch image having this thumb configuration canbe an indication that the touch sensitive device is being held andtherefore grounded. As such, negative pixel compensation can bedeactivated or reduced, if currently active, or can otherwise remaininactive, when the touch panel 61 generates a touch signal.

It is to be understood that the embodiments and parameters described inFIGS. 1 through 6 can be used individually or in various combinations todetect the grounded state of a touch sensitive device. It is further tobe understood that the embodiments and parameters are not limited tothose described herein, but can include additional and/or otherembodiments and parameters capable of being used for detecting thedevice's grounded state.

FIG. 7 illustrates an exemplary method for detecting a grounded state ofa touch sensitive device according to various embodiments. In theexample of FIG. 7, a determination can be made whether a touch event hasoccurred at a touch sensitive device (70). If so, a touch image of thetouch event can be captured by the device (71). Various parameters ofthe device can be checked (72). For example, the parameters as describedin FIGS. 1 through 6 can be checked. The parameters' values can beanalyzed to determine the grounded state of the device (73).

In some embodiments, the parameters' values can be binary, e.g., “state1” or “state 2,” “1” or “0,” “on” or “off,” “yes” or “no,” and so on.For example, the power connector values can be “yes” if the power cableis plugged into the wall and “no” if the power cable is either notplugged into the wall or not connected to the device.

In some embodiments, a single parameter value can be used to determinethat the device is grounded. For example, a power value indicating thatthe device is plugged into the wall can determine that the device isgrounded. In that case, other parameters' values can be discarded orotherwise ignored in the analysis. In some embodiments, multipleparameter values can be used to determine that the device is grounded.For example, a motion value indicating that the device is lyingstationary and flat, a proximity value indicating that the device islying on a wood table top, and a power value indicating that the deviceis not plugged into the wall can determine that the device is notproperly grounded. In such instances, other parameters' values can bediscarded or otherwise ignored in the analysis. In some embodiments, theparameter values can be weighted and the mathematical result (e.g., sum,product, ratio, etc.) of the weighted values can indicate the groundedstate, where parameters which are stronger or more determinativeindicators of the device's grounded state can have higher weights andparameters which are weaker or inconclusive indicators of the groundedstate can have lower weights. The mathematical result can be aparticular one of multiple possible values, e.g., an analog value,indicating the degree of grounding, or can be compared to a threshold,indicating “grounded” above the threshold and “not grounded” below thethreshold. In some embodiments, a lookup table can be used to determinewhether the device is grounded, where each entry of the lookup table caninclude a permutation of the possible parameters' values and a groundedstate based on that permutation.

In some embodiments, the grounded state can be a binary value, e.g.,grounded can be “yes” and not grounded can be “no.” In some embodiments,the grounded state can be a particular one of multiple possible values,e.g. an analog value, indicating the degree of grounding, e.g., rangingfrom grounded at 1.0 to not grounded at 0.0.

The following depict exemplary scenarios in which parameters of a touchsensitive device can be used to detect whether the device is grounded.In one example scenario, if the device is in a dock and plugged into thewall, a connector sensor in the device can sense that the power cable isplugged in to determine that the device is grounded. In another examplescenario, if the device is held in a user's hand, a motion sensor cansense the signature human vibration and the perimeter sensor can sensethe user's touch at the device to determine that the device is grounded.In another example scenario, if the device is in a dock and untouched,none of the parameters' values can likely provide information that candetermine whether the device is grounded. For example, the motion sensorcan sense an upright pose of the device and the proximity sensor canperhaps sense the dock being proximate to the device, but neither may besufficient to determine the grounded state, depending on the device. Inthis instance, a default determination can be made, e.g., that thedevice is not grounded. In one example scenario, if the device is in adock and being touched, the perimeter sensor can sense the user's touchat the device. However, the user may not be touching enough of thedevice to fully ground the device, which can result in a false positivedetermination that the device is grounded. As such, the absence of otherparameters, e.g., an indication from the connector sensor that the powercable is plugged in, can be used to determine, despite the perimetersensor value, that the device is either not or just partially grounded.In another example scenario, if the device is in a user's lap, themotion sensor can sense the signature human vibration and the proximitysensor can sense the user's lap under the device such that it can bedetermined that the device is grounded. In another example scenario, ifthe device is in a protective cover, the proximity sensor can sense thecover material such that it can be determined that the device is notgrounded.

Based on the determined grounded state of the device, a determinationcan be made whether to selectively apply negative pixel compensation andhow much, e.g., fully, partially, or not at all (74). If the determinedgrounded state is well grounded, negative pixel compensation can bedeactivated or reduced, if currently active, or can otherwise remaininactive. If the determined grounded state is anything else, negativepixel compensation can be adjusted, if currently active, or activated,if currently inactive. In terms of how much to apply, in someembodiments where the grounded state is a binary value, the amount ofnegative pixel compensation can also be a binary value, e.g., if thegrounded state is “yes,” the negative pixel compensation can be omittedor not applied at all, and if the grounded state is “no,” the negativepixel compensation can be applied fully.

In some embodiments where the grounded state can have one of multiplevalues, e.g. an analog value, the amount of negative pixel compensationto be applied can be scaled either up or down based on the extent thatthe device is grounded, i.e., based on the grounded value. For example,if the degree of grounding is 0.8, indicative of some grounding, theamount of negative pixel compensation can be decreased by 80% from apredetermined full amount, since less negative pixel effect is likely.Conversely, if the degree of grounding is determined to be 0.2,indicative of some, but not a significant amount of grounding, theamount of negative pixel compensation can be decreased by only 20% fromthe full amount, since a significant negative pixel effect is likely. Assuch, the amount of negative pixel compensation to be applied can beproportionate to the extent of the device grounding.

In some embodiments, the negative pixel compensation can be calculated.In some embodiments, the negative pixel compensation can bepredetermined, e.g., accessed from a lookup table.

The determined negative pixel compensation can be applied to the touchimage to adjust the touch signals, thereby reducing or eliminating anynegative pixel effects and providing more accurate touch signals (75).The adjusted touch image can be further processed to get touchinformation for use by the device (76).

This method can be repeated each time a touch event occurs at thedevice. Alternatively, this method can be repeated periodically betweenmultiple touch events, depending on the needs of the device.

FIG. 8 illustrates an exemplary computing system 80 of a touch sensitivedevice that can detect a grounded state of the device according tovarious embodiments described herein. In the example of FIG. 8,computing system 80 can include touch controller 84. The touchcontroller 84 can be a single application specific integrated circuit(ASIC) that can include one or more processor subsystems 84 a, which caninclude one or more main processors, such as ARM968 processors or otherprocessors with similar functionality and capabilities. However, inother embodiments, the processor functionality can be implementedinstead by dedicated logic, such as a state machine. The processorsubsystems 84 a can also include peripherals (not shown) such as randomaccess memory (RAM) or other types of memory or storage, watchdog timersand the like. The touch controller 84 can also include receive section84 g for receiving signals, such as touch signals 86 b of one or moresense channels (not shown), other signals from other sensors such assensor 85, as described above in FIGS. 1 through 6, for example. Thetouch controller 84 can also include demodulation section 84 b such as amultistage vector demodulation engine, panel scan logic 84 f, andtransmit section 84 e for transmitting stimulation signals 84 i to touchsensor panel 86 to drive the panel. The panel scan logic 84 f can accessRAM 84 c, autonomously read data from the sense channels, and providecontrol for the sense channels. In addition, the panel scan logic 84 fcan control the transmit section 84 e to generate the stimulationsignals 84 i at various frequencies and phases that can be selectivelyapplied to rows of the touch sensor panel 86.

The touch controller 84 can also include charge pump 84 d, which can beused to generate the supply voltage for the transmit section 84 e. Thestimulation signals 84 i can have amplitudes higher than the maximumvoltage by cascading two charge store devices, e.g., capacitors,together to form the charge pump 84 d. Therefore, the stimulus voltagecan be higher (e.g., 6V) than the voltage level a single capacitor canhandle (e.g., 3.6 V). Although FIG. 8 shows the charge pump 84 dseparate from the transmit section 84 e, the charge pump can be part ofthe transmit section.

Touch sensor panel 86 can include a capacitive sensing medium having rowtraces (e.g., drive lines) and column traces (e.g., sense lines),although other sensing media can also be used. The row and column tracescan be formed from a transparent conductive medium such as Indium TinOxide (ITO) or Antimony Tin Oxide (ATO), although other transparent andnon-transparent materials such as copper can also be used. In someembodiments, the row and column traces can be perpendicular to eachother, although in other embodiments other non-Cartesian orientationsare possible. For example, in a polar coordinate system, the sense linescan be concentric circles and the drive lines can be radially extendinglines (or vice versa). It should be understood, therefore, that theterms “row” and “column” as used herein are intended to encompass notonly orthogonal grids, but the intersecting traces of other geometricconfigurations having first and second dimensions (e.g. the concentricand radial lines of a polar-coordinate arrangement). The rows andcolumns can be formed on, for example, a single side of a substantiallytransparent substrate separated by a substantially transparentdielectric material, on opposite sides of the substrate, on two separatesubstrates separated by the dielectric material, etc.

At the “intersections” of the traces, where the traces, pass above andbelow (cross) each other (but do not make direct electrical contact witheach other), the traces can essentially form two electrodes (althoughmore than two traces can intersect as well). Each intersection of rowand column traces can represent a capacitive sensing node and can beviewed as picture element (pixel) 86 a, which can be particularly usefulwhen the touch sensor panel 86 is viewed as capturing an “image” oftouch. (In other words, after the touch controller 84 has determinedwhether a touch event has been detected at each touch sensor in thetouch sensor panel, the pattern of touch sensors in the multi-touchpanel at which a touch event occurred can be viewed as an “image” oftouch (e.g. a pattern of fingers touching the panel).) The capacitancebetween row and column electrodes can appear as a stray capacitanceCstray when the given row is held at direct current (DC) voltage levelsand as a mutual signal capacitance Csig when the given row is stimulatedwith an alternating current (AC) signal. The presence of a finger orother object near or on the touch sensor panel can be detected bymeasuring changes to a signal charge Qsig present at the pixels beingtouched, which can be a function of Csig.

Computing system 80 can also include host processor 82 for receivingoutputs from the processor subsystems 84 a and performing actions basedon the outputs that can include, but are not limited to, moving anobject such as a cursor or pointer, scrolling or panning, adjustingcontrol settings, opening a file or document, viewing a menu, making aselection, executing instructions, operating a peripheral deviceconnected to the host device, answering a telephone call, placing atelephone call, terminating a telephone call, changing the volume oraudio settings, storing information related to telephone communicationssuch as addresses, frequently dialed numbers, received calls, missedcalls, logging onto a computer or a computer network, permittingauthorized individuals access to restricted areas of the computer orcomputer network, loading a user profile associated with a user'spreferred arrangement of the computer desktop, permitting access to webcontent, launching a particular program, encrypting or decoding amessage, and/or the like. The host processor 82 can also performadditional functions that may not be related to panel processing, andcan be coupled to program storage 83 and display device 81 such as anLCD display for providing a UI to a user of the device. In someembodiments, the host processor 82 can be a separate component from thetouch controller 84, as shown. In other embodiments, the host processor82 can be included as part of the touch controller 84. In still otherembodiments, the functions of the host processor 82 can be performed bythe processor subsystem 84 a and/or distributed among other componentsof the touch controller 84. The display device 81 together with thetouch sensor panel 86, when located partially or entirely under thetouch sensor panel or when integrated with the touch sensor panel, canform a touch sensitive device such as a touch screen.

A grounded state of the touch sensitive device can be determined by theprocessor in subsystem 84 a, the host processor 82, dedicated logic suchas a state machine, or any combination thereof based on inputs from thesensors 85 and other information, according to various embodiments.

Note that one or more of the functions described above can be performed,for example, by firmware stored in memory (e.g., one of the peripherals)and executed by the processor subsystem 84 a, or stored in the programstorage 83 and executed by the host processor 82. The firmware can alsobe stored and/or transported within any computer readable storage mediumfor use by or in connection with an instruction execution system,apparatus, or device, such as a computer-based system,processor-containing system, or other system that can fetch theinstructions from the instruction execution system, apparatus, or deviceand execute the instructions. In the context of this document, a“computer readable storage medium” can be any medium that can contain orstore the program for use by or in connection with the instructionexecution system, apparatus, or device. The computer readable storagemedium can include, but is not limited to, an electronic, magnetic,optical, electromagnetic, infrared, or semiconductor system, apparatusor device, a portable computer diskette (magnetic), a random accessmemory (RAM) (magnetic), a read-only memory (ROM) (magnetic), anerasable programmable read-only memory (EPROM) (magnetic), a portableoptical disc such a CD, CD-R, CD-RW, DVD, DVD-R, or DVD-RW, or flashmemory such as compact flash cards, secured digital cards, USB memorydevices, memory sticks, and the like.

The firmware can also be propagated within any transport medium for useby or in connection with an instruction execution system, apparatus, ordevice, such as a computer-based system, processor-containing system, orother system that can fetch the instructions from the instructionexecution system, apparatus, or device and execute the instructions. Inthe context of this document, a “transport medium” can be any mediumthat can communicate, propagate or transport the program for use by orin connection with the instruction execution system, apparatus, ordevice. The transport medium can include, but is not limited to, anelectronic, magnetic, optical, electromagnetic or infrared wired orwireless propagation medium.

It is to be understood that the touch sensor panel is not limited totouch, as described in FIG. 8, but can be a proximity panel or any otherpanel according to various embodiments. In addition, the touch sensorpanel described herein can be either a single-touch or a multi-touchsensor panel.

It is further to be understood that the computing system is not limitedto the components and configuration of FIG. 8, but can include otherand/or additional components in various configurations capable ofdetecting the device's grounded state according to various embodiments.

FIG. 9 illustrates an exemplary mobile telephone 90 that can includetouch sensor panel 92, display 93, and other computing system blocksthat can detect the telephone's grounded state according to variousembodiments.

FIG. 10 illustrates an exemplary digital media player 100 that caninclude touch sensor panel 102, display 103, and other computing systemblocks that can detect the player's grounded state according to variousembodiments.

FIG. 11 illustrates an exemplary personal computer 110 that can includetouch sensor panel (trackpad) 112, display 113, and other computingsystem blocks that can detect the computer's grounded state according tovarious embodiments.

The mobile telephone, media player, and personal computer of FIGS. 9through 11 can realize power savings, improved accuracy, faster speed,and more robustness by detecting their grounded states according tovarious embodiments.

Although parameters of the touch sensitive device are described hereinas being used to detect the grounded state of the device, it is to beunderstood that these and/or other parameters can bemused for otherpurposes associated with the device. For example, parameters can be usedto adjust the radiation output of the device to reduce radiationexposure during usage. Parameters can also be used to adjust theoperation of the device to reduce power or other components based on thecurrent usage of the device.

To adjust the radiation output, parameters of the touch sensitive devicecan be checked to determine the orientation of the device and theproximity of the device to the user. The parameters' values can beanalyzed to determine whether the device is currently being held uprightnext to the user, e.g., whether the user is making a call on the deviceand is holding the device upright against an ear or at the mouth. Forexample, a motion sensor output as previously described can indicate thedevice's orientation and motion, a proximity sensor output as previouslydescribed can indicate whether the device is proximate to a user, aperimeter sensor output as previously described can indicate whether thedevice is being held, a touch sensor panel output as previouslydescribed can also indicate whether the device is being held, anotification algorithm as previously described can indicate whether thedevice is currently executing a telephone application, a connectionoutput as previously described can indicate whether the device isplugged in, and so on. If the device is determined to be held uprightnext to the user, the radiation output of the device can be adjusted,e.g., reduced, to limit the user's radiation exposure. The parameters'values can be either continuously or periodically checked and analyzedsuch that when the user moves the device to a flat position or away fromthe user, the radiation output of the device can be adjusted again,e.g., returned to its initial output.

To adjust the usage of the device, parameters of the touch sensitivedevice can be checked to determine how the device is currently beingused, e.g., whether the device is currently in a holster carried by auser, at a location away from the user, or in the user's hand. Forexample, a motion sensor output as previously described can indicate thedevice's orientation and motion, a proximity sensor output as previouslydescribed can indicate whether the device is proximate to a user or anobject, a perimeter sensor output as previously described can indicatewhether the device is being held, a touch sensor panel output aspreviously described can also indicate whether the device is being held,a notification algorithm as previously described can indicate whetherthe device is currently executing an application or is idle, aconnection output as previously described can indicate whether thedevice is plugged in, and so on. If the device is determined to be at alocation away from the user, the ring tone can be increased so that theuser can more easily hear a ring indicating an incoming call. If thedevice is determined to be in the holster, the ring tone can be switchedto vibration mode so that the user can feel a vibration indicating anincoming call. If the device is determined to be in the user's hand, thering tone can be decreased or deactivated since the device is likely inuse. In addition or alternatively, if the device is in the holster or ina location away from the user, the power consumption can be reduced toconserve power since the holster or the away location can be indicativeof idle time or non-usage. The parameters' values can be eithercontinuously or periodically checked and analyzed for change in use.

FIG. 12 illustrates an exemplary method for detecting a state of a touchsensitive device according to various embodiments. In the example ofFIG. 12, parameters of the touch sensitive device can be checked (120).The parameters' values can be analyzed to determine the state of thedevice (122). For example, the parameters can be analyzed to determinewhether the device is upright proximate to a user or whether the deviceis in a holster or a hand, as described previously. Based on theanalysis, the device can be adjusted (124). For example, the device'soutputs and/or operation can be adjusted.

It is to be understood that the method is not limited to a touchsensitive device, but can be applied to other portable devices, as wellas stationary devices, for which a grounded state (or any other state)can be detected.

Although embodiments have been fully described with reference to theaccompanying drawings, it is to be noted that various changes andmodifications will become apparent to those skilled in the art. Suchchanges and modifications are to be understood as being included withinthe scope of the various embodiments as defined by the appended claims.

What is claimed is:
 1. A touch sensitive device comprising: at least onedevice component configured to provide an output indicative of a stateof the device, the at least one device component including a motionsensor or a proximity sensor; a touch sensing component configured tosense a touch at the device and to output one or more touch signalsassociated with the sensed touch; and a processor configured todetermine a grounding condition of the device based on at least one ofthe output of the motion sensor or proximity sensor, and apply afunction selectively to compensate one or more touch signals having anegative touch output value when the grounding condition is indicativeof negative capacitance introduced into the device.
 2. The device ofclaim 1, wherein the device component is at least one of a connectorsensor configured to sense a component connection to the device, aresistor detector configured to detect a resistor connection to thedevice, a motion sensor configured to sense at least one of motion ororientation of the device, a proximity sensor configured to sense asurface proximate to the device, a perimeter sensor configured to sensean object in contact with a perimeter of the device, a property sensorconfigured to sense a property of an object proximate to the device, oran application indicator configured to indicate what type of applicationthe device executes.
 3. The device of claim 2, wherein the processor isconfigured to determine the grounding condition of the device based onat least one of the component connection, the resistor connection, thedevice motion, the device orientation, the proximate surface, theperimeter contact, or the executed application.
 4. The device of claim1, wherein the touch sensing component is configured to determine theportion of an object touching the device according to the touch signal.5. The device of claim 4, wherein the processor is configured todetermine the grounding condition of the device based on the determinedtouching portion of the object.
 6. The device of claim 1, wherein thefunction reduces an error introduced into the one or more touch signalswhen the device is poorly grounded.
 7. The device of claim 1, whereinthe processor is configured not to apply the function when the groundingcondition is not indicative of negative capacitance introduced into thedevice.
 8. The device of claim 1 incorporated into at least one of amobile telephone, a digital media player, or a personal computer.
 9. Amethod comprising: capturing one or more touch signals indicative of atouch at a touch sensitive device; providing, with one or more devicecomponents including a motion sensor or a proximity sensor, an outputindicative of at least one parameter value associated with a status ofthe device; determining a grounding condition of the device based on theoutput of the motion sensor or the proximity sensor; and applying afunction selectively to compensate the one or more touch signals havinga negative touch output value when the grounding condition is indicativeof negative capacitance introduced into the device.
 10. The method ofclaim 9, wherein providing the parameter value comprises providinginformation corresponding to at least one of whether the device isplugged into a wall outlet, whether the device is coupled to a groundeddevice, or whether the device is in physical contact with a user. 11.The method of claim 9, wherein determining the grounding conditioncomprises determining whether the parameter value is indicative of agrounded state of the device.
 12. The method of claim 9, whereindetermining the amount of adjustment comprises determining that noadjustment is required when the grounding condition is not indicative ofnegative capacitance introduced into the device.
 13. The method of claim9, wherein determining the amount of adjustment comprises determiningthe extent to which negative capacitance is introduced into the deviceand scaling an adjustment amount of compensation proportionate to thedetermined extent.
 14. The method of claim 9, comprising adjusting theone or more touch signals using the determined amount of compensation.15. A touch sensitive device comprising: one or more input componentsincluding a motion sensor or a proximity sensor; a touch sensor panelcomprising multiple touch nodes, each touch node configured to output atouch signal indicative of a touch event at the device; and a processorconfigured to analyze one or more inputs from the input components,determine a grounding condition of the device based on the analyzedinputs of the motion sensor or the proximity sensor, and apply afunction to selectively compensate one or more touch signals having anegative touch output value when the grounding condition is indicativeof negative capacitance introduced into the device.
 16. The device ofclaim 15, wherein the processor is configured to determine the extent towhich negative capacitance is introduced into the device and scale anadjustment amount of compensation proportionate to the determinedextent.
 17. The device of claim 16, wherein the processor is configuredto adjust the one or more touch signals using the determined amount ofcompensation.
 18. The device of claim 15, wherein the processor isconfigured to determine that no adjustment is required when thegrounding condition is not indicative of negative capacitance introducedinto the device.
 19. The device of claim 15, wherein, when the groundingcondition corresponds to the device being poorly grounded or beingpartially grounded, the processor is configured to activate the providedfunction to compensate the one or more touch values of the touch nodesfor error introduced by the device into the touch values as a result ofthe device being poorly grounded or being partially grounded.